Add info about fileIds.txt, update version num

Update README.md

Fix padding math error + some minor pindex differences

Add support for .pindex/.patch files + add --createPatch option

Extracting from .pindex files should work fine, read the readme to learn
more about them.

--createPatch also seems to work (tested editing a small decl with it and
the game happily showed my changes, with some convincing from
"+devMode_enable 1" of course :)
Repacking .pindex files also seems to work too (note: you should only
edit/rebuild the latest patch file, and never the base .index file, as
patches depend on the data in earlier files!)
Haven't tested a repacked .pindex ingame though, but --createPatch uses
the same code so I'm guessing it works, any problems please let me know!

(on a different note, it seems the .verify files might actually be
HMAC-SHA256 hashes and not signatures... somebody determined enough could
probably forge them for modified files, but that somebody won't be me :P)

Fix small bug that breaks repacked resources

Seems to repack the resources properly now, haven't tested with mods yet
though but hopefully they'll work the same as they did in the betas (might
require "devMode_enable 1" launch parameter though)

DOOMExtract 1.5 - changes method used to extract files, not fully tes…

…ted!